A team of scientists from Temple University School of Medicine and the University of Pennsylvania has moved another step closer to solving a decades-long mystery of how the all-important flow of calcium into the cell's power source, the mitochondria, is controlled. By painstakingly shutting down the activity of 50 genes, one at a time, they have identified a protein, MCUR1, which hugs the inside of the mitochondrial membrane and is part of an elaborate mitochondrial channel pore system. MCUR1 acts as an accelerator to help regulate calcium coming into the mitochondria from the cell's large reservoir.